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array manipulation
3 messages · Simone Salvadei, David Winsemius, Patrick Burns
On Nov 2, 2011, at 12:16 PM, Simone Salvadei wrote:
Hello, I'm at the very beginning of the learning process of this language. Sorry in advance for the (possible but plausible) stupidity of my question. I would like to find a way to permute the DIMENSIONS of an array. Something that sounds like the function "permute()" in matlab. Given an array C of dimensions c x d x T , for instance, the command permute(C, [2 1 3])
?aperm
would provide (in Matlab) an array very similar to C, but this time
each
one of the T matrices c x d has changed into its transposed.
Any alternatives to the following (and primitive) 'for' cycle?
*# (previously defined) phi=array with dimensions c(c,d,T)*
*
*
*temp=array(0,dim=c(c,d,T))*
* for(i in 1:T)*
* {*
* temp[,,i]=t(phi[,,i])*
* }*
* phi=temp*
*
*
David Winsemius, MD Heritage Laboratories West Hartford, CT
You seem to be looking for 'aperm'. There is a chapter in 'S Poetry' (available on http://www.burns-stat.com) that talks about working with higher dimensional arrays. I don't think any changes need to be made for R.
On 02/11/2011 16:16, Simone Salvadei wrote:
Hello,
I'm at the very beginning of the learning process of this language.
Sorry in advance for the (possible but plausible) stupidity of my question.
I would like to find a way to permute the DIMENSIONS of an array.
Something that sounds like the function "permute()" in matlab.
Given an array C of dimensions c x d x T , for instance, the command
permute(C, [2 1 3])
would provide (in Matlab) an array very similar to C, but this time each
one of the T matrices c x d has changed into its transposed.
Any alternatives to the following (and primitive) 'for' cycle?
*# (previously defined) phi=array with dimensions c(c,d,T)*
*
*
*temp=array(0,dim=c(c,d,T))*
* for(i in 1:T)*
* {*
* temp[,,i]=t(phi[,,i])*
* }*
* phi=temp*
*
*
Thank you very much!
S
Patrick Burns pburns at pburns.seanet.com twitter: @portfolioprobe http://www.portfolioprobe.com/blog http://www.burns-stat.com (home of 'Some hints for the R beginner' and 'The R Inferno')